I'm soon to plant out a bunch of Dianthus seedlings that I have been growing this Winter. I'm thinking of starting a crevice garden with some of these in this or another bed, but I wanted to simply grow these plants for a year to get to know their habit first. The soil that is currently in the bed is a mixture of commercial soils and ammendments put in by the landscaper. It drains well and is neutral to very slightly acid. My plan, though, is to add another two to three inches of soil to the top (it's settled quite a bit). Knowing that I'd like to grow out these Dianthus, I'm looking for advice as to the optimal materials to add here for these plants. Varieties include alpinus, arenarius, fragrans, plumarius and supurbus, along with another four mystery varietys from a mixed packet. FWIW I'm in Central Oregon Zone 6a at about 3000'. The bed is essentially in full sun. Thanks!